Color image recording apparatus that record color image information using a recording method such as ink jet, heat transfer or electrophotography are well known.
FIG. 2 is a block diagram for processing a signal in a color image recording apparatus of this type. An image reader or an image data storage, not shown, outputs three color image signals 1a, 1b and 1c indicative of yellow, magenta and cyan, respectively, which are input to a color correction unit 2 which performs a color correction such as masking on these input signals. A gradation correction unit 3 performs a gradation correction on the corrected color signals from color correction unit 2. A printer 4 forms yellow, magenta and cyan images in accordance with the corrected gradation signals and records a color image.
An apparatus of this type is most desired to reproduce a color faithful to that of an input image. In some cases, it may be desired to output an image by changing a color of the input image. For example, in the design of a poster, it may be desired to reproduce an original image in various colors. Especially, it is strongly desired to change only a particular color portion of the original image to another color to output the resulting image.
U.S. Pat. No. 4,204,728 discloses an electronic color photography reproduction apparatus (color electrophotographic copying apparatus) which focuses an optical image passing through R-, G- and B- filters onto a photosensitive medium and develops the same using developers of cyan, magenta and yellow. In such related art, however, not only the particular color in the original image but also other colors containing the color components (Y, M, C) contained in the particular color may be changed. Even in a color image recording apparatus which temporarily changes a color image into color component signals and records the colors, if colors not corresponding to three color (yellow, magenta and cyan) signals are printed with the yellow, magenta and cyan color signals, an image different in color from the input image can be produced. For example, if magenta, cyan and yellow are printed with yellow, magenta and cyan signals, respectively, the red portion of yellow+magenta, the blue portion of magenta+cyan and the green portion of cyan+yellow will be reproduced with the blue of magenta+cyan+yellow will be reproduced with the blue of magenta+cyan, the green of cyan+yellow, and the red portion of yellow+magenta, respectively. However, according to such method, all colors of the input image except for three monochromatic elements, yellow, magenta and cyan, will be reproduced in different colors from those of the original image, so that it is impossible to replace only a particular color with another.
U.S. Pat. No. 4,538,182 discloses a color reproduction apparatus which reproduces a plurality of particular colors, for example, two colors (red and black) or three colors (red, blue and black), in which the original red will be changed to black or the original black will be changed to red. However, it is impossible to change a delicate color including a plurality of color components to another or to change a color to a plurality of delicate color components.